Sealed container having a zirconium tin alloy getter

ABSTRACT

A getter for gases contained within a hermetically sealed container including gases dissolved in the container walls to be maintained substantially free of such gases and disposed within the container a body heatable to an elevated temperature, the getter consisting essentially of a zirconium-base alloy containing from about 10 to about 30 weight per cent tin.

its @ttes atent [1 1 Gulbransen et a1.

[ SEALED CONTAlNER HAVENG A ZlRCONlUM-TIIN ALLOY GETTER [75] Inventors: Earl A. Gulbransen; Sven A.

Jransson, both of Pittsburgh, Pa.

(73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

221 Filed: Apr. 30, 1968 21 Appl. No.: 725,337

Related US. Application Data [63] Continuation-impart of Ser. No. 696,417, Jan. 8,

1968, abandoned.

206/04, 313/174 [51] lnt. Cl G21c 3/02, G21c 19/32 [58] Field ot Search 176/68, 70, 37;

[56] References Cited UNITED STATES PATENTS 2,154,131 4/1939 Lederer 252/1812 X 2,758,239 8/1956 Schmidt 313/174 2:926:931 3/1960 Stout et al. 75/177 X 3,054,914 9/1962 l-latsopoulos et al. 310/4 3,1 l5,446 12/1963 Finniston 176/37 X 3,147,088 9/1964 Kalish 75/177 X 3,243,350 3/1966 Lustman et al.... 75/177 X 3,275,522 9/1966 Kinsey ct al. 176/68 X Primary Examiner-Carl D. Quarforth Assistant Examiner-Gary Solyst AttorneyF. Shapoe and L. P. Johns [57] ABSTRACT A getter for gases contained within a hermetically sealed container including gases dissolved in the container walls to be maintained substantially free of such gases and disposed within the container a body heatable to an elevated temperature, the getter consisting essentially of a zirconium-base alloy containing from about 10 to about 30 weight per cent tin.

6 Claims, 7 Drawing Figures PATENTEDHET 2 3.782.995

SHEET 10F 2 INVENTORS Earl A. Gulbronsen 0nd ven A. Jan son BY 9 2 ATTO NEY SEALED CONTATNER HAVTNG A ZTIRCONTUM-TTN ALLOY (BETTER CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of copending application Ser. No. 696,417, filed Jan. 8, 1968 now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a getter for absorbing certain gases within the interior of a sealed container including gases dissolved in the container walls at ele 'vated temperatures. More particularly, it pertains to a getter composed of a zirconium-base alloy containing a relatively large amount of the intermetallic Zr Sn such as about 24.5 percent tin.

2. Description of the Prior Art A getter is a material used to absorb residual traces of gases and vapors such as remaining in an evacuated electron discharge device during and after the mechanical exhaust process. Such gases are occluded or adsorbed on the various surface portions of the device. At room temperature the getter is usually inert but becomes highly active when heated. Usually the getter is volatilized upon initial use of an electron discharge de vice and thereby adsorbs the traces of residual gas by chemical and/or physical action.

Various elements including tantalum, titanium, ce rium, thorium hafnium, and zirconium are well known gettering materials. Unalloyed zirconium has been useful as a getter in many environments. For example, in tungsten filament lamps pure zirconium has been used to lower the concentrations of residual gases which are evolved during operation of the lamp from glass and metal surfaces. The water molecules for example are not all removed when the lamp bulb is exhausted during manufacture. As a result, during use of the lamp the water outgasses over extended periods of time.

One disadvantage of zirconium metal as a gettering material in such an atmosphere is that the metal readily forms a protective surface oxide which reduces and limits its subsequent reactivity. The traces of water vapor and oxygen react with the tungsten of the filament to form volatile oxides of tungsten which con dense upon cooling on the inner surface of the lamp bulb and on cooler portions of the filament and filament support and form tungsten and water vapor. The tungsten as well as certain tungsten oxides accumulate on the glass envelope of the incandescent lamp. Meanwhile, the water vapor again reacts with the tungsten filament to form the various volatile tungsten oxides whereby the cycle continues until the tungsten filament fails.

In other devices such as vacuum switches having copper or copper and titanium electrodes which are maintained in a sealed tube at a pressure of about Torr during the expected life of the switch. During the manufacture of the switch complex cleaning and high vacuum bakeout procedures are required to prevent premature failure of the electrodes. Notwithstanding such procedures occluded gases such as oxygen and water vapor, as well as gases released during the operation of the switch such as hydrogen, carbon monoxide, and carbon dioxide are present and must be eliminated to prevent early failure of the switch. Such gases and vapors are readily and substantially completely removed drogen and nitrogen as well as watervapor from the by the use of a proper gettering material as will be detailed hereinafter.

A nuclear fuel element is another type of hermetically sealed container in which a getter is useful. One reason for that is that cladding for fuel element is designed to withstand upper limits of internal and external fluid pressure.

Where the cladding thickness is minimized to improve neutron economy, the differential of the internal and external fluid pressures acting on the cladding should remain relatively constant. During operation of a reactor the internal gas pressure gradually increases partially because of the evolution of such gases as hyuranium oxide fuel pellets and from occluded or ad sorbed gases on the inner surface of the cladding. Fission gases such as xenon and krypton are also released but the pressures of these gases are normally compensated for in calculating the thickness of the cladding. The amounts of hydrogen, nitrogen, and water vapor are not readily calculable because their presence varies with the conditions of sintering the U0 pellets. Moreover, traces of CO and C0 are found as a result of binders in lubricants used for compacting the U0 powder into pellet form prior to sintering. Such gases and vapors except xenon and krypton are readily and substantially completely removed by the use of a proper gettering material.

The absorption of the gases within a hermetically sealed fuel element is necessary for preventing premature failure of the cladding. Small amounts of hydrogen resulting from the corrosion of the zirconium alloy cladding in water or steam are absorbed by the cladding. This leads to hydrogen embrittlement of the clad ding, particularly upon cooling to room temperature, because of the corresponding decrease in hydrogen solid solubility and the precipitation of hydride. The deleterious effects of hydrogen absorption of the cladding is minimized by incorporating internally in the fuel elements a getter for hydrogen. The getter must be capable of absorbing more hydrogen in solid solution than the zirconium alloy cladding, when in contact with the cladding under reactor operating conditions.

Associated with the foregoing is the problem of hydrogen embrittlement in other portions of a nuclear reactor. A pressure vessel of a water cooled reactor is illustrative of such a portion. During operation of a reactor the pressure vessel may absorb hydrogen gas'from the coolant water. To avoid the ultimate failure of the vessel wall due to cracking caused by excessive hydrogen embrittlement a gettering material may also be used on or even in the vessel wall to absorb hydrogen.

In accordance with this invention, various other hermetically sealed devices currently in use, other than incandescent lamps, vacuum switches, nuclear fuel elements, and reactor vessels likewise produce a buildup of gas pressure or produce conditions for hydrogen embrittlement due to a series of complex chemical reactions which gas pressures may be minimized by the use of the proper gettering material.

It has been found in accordance with this invention that the foregoing difficulties may be overcome by the use of a zirconium-base tin alloy consisting essentially of from 10 to 30 percent tin, balance zirconium, with incidental impurities, containing the intermetallic alloy compound Zr Sn, which alloy at a temperature gradient varying from about 300 to 700C is outstandingly efficient in removing to a very low concentration various undesirable residual gases from a hermetically sealed enclosure, such gases including oxygen, carbon dioxide, carbon monoxide, hydrogen, nitrogen and water vapor. Ultra high vacuums may be maintained by the use of this alloy.

Accordingly, it is a general object of this invention to provide a zirconium base tin alloy as a getter for adsorbing traces of residual and evolved gases from a hermetically sealed container.

It is another object of this invention to provide a zirconium base tin alloy which functions at a temperature range of from about 300 to about 700C, over which temperature range various residual gases are most effect'ively adsorbed "by the alloy.

It is another object of this invention to provide a zirconium base tin alloy which forms an oxide coating which is less passive to the reaction of the alloy with additional oxygen and water vapor than is the oxide coating or unalloyed zirconium metal.

Finally, it is an object of this invention to satisfy the foregoing objects and desiderata in a simple and effective manner.

SUMMARY OF THE INVENTION Generally, the device of the present invention involves a zirconium binary alloy containing tin in an amount varying from about to about 30 weight per cent, and preferably 24.5 weight per cent for use in a hermetically sealed container as a getter in which container traces of residual gases are present and/or developed during operation of the container at elevated temperatures.

BRIEF DESCRIPTION OF THE DRAWING For a better understanding of the nature and objects of this invention, reference is made to the following detailed description and drawings, in which:

FIG. l is a vertical sectional view, partly in elevation, of an incandescent lamp which lamp is provided with a gettering member;

FIG. 2 is an enlarged sectional view of the type of lamp filament shown in FIG. I, and showing a gettering member in another form;

FIG. 3 is an elevational view, partly in section, of a lamp filament and having a gettering member attached thereto;

FIG. 4 is a vertical sectional view of a circuit interrupter embodying the one form of the invention;

FIG. 5 is a vertical sectional view of a nuclear fuel element having a body of gettering material contained therein;

FIG. 6 is a vertical sectional view of another embodiment of a nuclear fuel element; and

FIG. 7 is an elevational view, partially in section, of a nuclear reactor pressure vessel embodying an exemplary arrangement of this invention.

Similar numerals refer to similar parts throughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODlMENTS An incandescent lamp is generally indicated at I0 in FIG. l and, for example, is a standard 100 watt lamp designed for operation from a 110 volt line. It comprises a light-transmitting vitreous envelope 32, conventional reentrant stem press M sealed at the neck of the envelope l2, and filament-supporting lead conductors l6 sealed through the reentrant stem press and electrically connected to a lamp base 118. The envelope 12 may be clear or may have an inside-frost or other light-diffusing medium.

An incandescent filament 20 electrically connects between the inwardly-extending extremities of the lead conductors 36 within the envelope l2 and such a filament is normally fabricated of coiled -or coiled-coil tungsten as is usual, although the filament may be fabricated of other suitable refractory material. A body 22 of the gettering material is mounted on one of the conductors l6 and may be disposed either (as shown) or below the position of an arbor button Zft at the upper end of the stem press 14.

The body 22 of gettering material comprises a binary alloy of zirconium containing from about 10 weight per cent to about 30 weight per cent tin. A composition containing 24.5 weight per cent tin is most suitable.

As shown in FIG. 1 the body 22 is an elongated member having an upper end nearer the filament 20 than a lower end. When the filament 20 is incandescent at a temperature of approximately 2,600 to 3,000l(, the upper end of the body 22, being more proximate to the filament, is heated to a temperature of about 700C and the lower end of the body is heated to a temperature of about 300C, whereby a temperature gradient exists throughout the length of the body 22.

Ordinarily, a tungsten filament lamp of the type shown in FIG. 1 contains an argon-nitrogen gas mixture with traces of oxygen, water vapor, hydrogen, and other gases. These gases arise from several sources including impurities in the fill gas, residual gases in the lamp, and degassing of the lamp during use. During operation of the lamp, a number of chemical reactions occur between the hot tungsten filament and the active impurity gases. Oxygen can react with any hydrogen present to form water. Unreacted oxygen and water vapor react with tungsten to form a number of volatile, solid, and liquid tungsten oxides.

The hydrogen-water vapor mixture reduces the gaseous or condensed tungsten oxides to form lower tungsten oxides and tungsten, which can be redeposited on the glass or other surfaces. Because water is reformed, the oxidation of the tungsten filament and the reduction of tungsten oxides at lower temperatures can be repeated continuously causing a transfer of tungsten from the filament to the cooler lamp envelope 12. Two temperature regions are involved which cause the socalled water vapor cycle" to occur. These regions include the tungsten filament which operates at the high temperature region of 2,600 to 3,000K where oxidation and volatilization occur. The other region at a lower temperature of about 400 to 500K at the inner surface of the envelope 12 permits condensation and reduction of the volatile oxides. The several reactions are shown in the following formulas:

nine/two 0 3W (WO (g) Accordingly, any traces of oxygen initially present react with any hydrogen within the envelope to form water during operation and this with the tungsten filament to form volatile tungsten oxides. Likewise, after a brief initial period of operation, the active gases inelude a mixture of hydrogen and water vapor with only very minute amounts of oxygen present as determined by the H -l-I OO equilibrium for the various temperatures. Moreover, if carbon dioxide and carbon monoxide are present in the lamp, a second oxidizing and reducing gas mixture exists. Accordingly, tungsten can be transferred from the filament to the walls of the envelope by a similar series of reactions to those occurring in a water vapor-hydrogen mixture.

Zirconium getters have been used to lower the residual gas content in tungsten filament lamps. However, zirconium metal has the property of forming a protective oxide which limits subsequent reactivity of zirco nium. The zirconium-tin alloy has two advantages over other getters including unalloyed zirconium metal. First, the reaction of the binary alloy with both hydrogen and oxygen is faster than for zirconium metal. The alloy may be used at lower temperatures than unalloyed zirconium metal. A temperature range of from about 500 to 700C is suggested for best removal of oxygen and water vapor, while a temperature of about 300C may be used for the removal of hydrogen gas. Second, the binary alloy (Zr-Sn) reacts with hydrogen without change of phase, i.e., zirconium hydride is not formed. This minimizes the possibility that spalling of zirconium hydride from the alloy will occur.

For example, at 292C, a zirconium base binary alloy in the amount of l3.7 mg and containing 24.5 weight per cent tin removes g of hydrogen gas or about 900 cc of hydrogen at an equilibrium pressure of 10 Torr. Likewise, 180 cc of hydrogen would be removed at that temperature with a residual pressure of 10 Torr. At even lower pressures smaller amounts of hy drogen are removed. The amounts of the zirconium-tin binary alloy necessary depends upon the size of the lamp and the pressure level of impurity gases to be removed.

As shown in FlG. l, the body 22 of getter material is disposed with the upper end approximate to the filament whereby the upper end attains a temperature of about 700C and the lower end at a temperature of about 300C with a temperature gradient therebetween. As a result, water vapor molecules are adsorbed at the upper end of the body 22 where the zirconium alloy reacts with oxygen in the water in accordance with a two stage reaction as shown in the following formulas:

Zr 0 e Zr 2 0 in solid solution Zr 0 ZrO film on surface As a result of the foregoing reactions the hydrogen reacts with zireonium alloy in accordance with the following formula:

Zr H Zr 2H in solid solution Due to the higher solubility of hydrogen in the intermetallic alloy at low temperature hydrogen diffuses to the cold end of the getter where it is concentrated in solid solution.

A binary alloy of zirconium and tin has the advantage of higher reactivity with water vapor than unalloyed zirconium metal. The reaction of the alloyed zirconium with hydrogen is practically instantaneous as compared with zirconium alone. The use of a getter operative at two different temperatures, or over a temperature gra' dient, provides the advantage of rapid reaction at the hot end and easy transport by diffusion to the more ef fective low temperature absorption sink. Thus, the zirconium binary alloy with tin may be used to remove both oxygen and hydrogen if the getter were operated at a temperature gradient where the hot end is at a high temperature, e.g. 700C, and the cool end is near 300C.

Another form of the invention is shown in FIG. 2 in which a body of getter material in the form of a wire coil 26 is mounted between the lead conductors 16 and on a support wire 28. Inasmuch as the coil 26 has a resistance substantially higher than that of the tungsten filament 20 a small amount of current heats the coil to the desired temperature, namely, 700C at the center. Opposite end portions 27 of the coil 26, extending outwardly from the lead conductors l6, are heated only to a temperature of about 300C. The coil 26 is preferably composed of the zirconium base binary alloy with tin which composition is comparable to that of the body to of FIG. l. The coil may preferably be composed of a zirconium base binary alloy containing about 24.5 weight per cent tin or having the intermetallic supported on an auxiliary heater coil which could be any metal having the proper resistance.

Another form of the invention is shown in FIG. 3 in which an upper portion of a coil 30 is wound around one of the lead conductors 16 of the type of incandescent lamp 10. The filament 20 is operated at the usual incandescent temperature range, namely, 2,600 to 3,000K. Because of its proximity to the filament 20, the upper portion of the coil 30 is heated by convection and radiation to a temperature of about 700C. A lower portion 32 of the coil extends outwardly from the conductor 16 and, being more remote from the filament 20, sustains a temperature of about 300C when the filament is operated. The coil 30, a getter material which is preferably consisting essentially of a zirconium tin binary alloy having about 24.5 weight per cent tin, operates as a temperature gradient body for adsorbing traces of residual gases of oxygen, hydrogen and water from the surrounding atmosphere.

Still another form of the invention is shown in FIG. 4 which depicts a highly evacuated container or envelope 34 comprising a casing 36 and a pair of metallic end caps 38 and 40 closing the end of the casing. Suitable seals 42 are provided between the end caps and the casing to render the envelope vacuum tight. The normal pressure within the envelope 34 under steady conditions is lower than 10 mm of mercury, so that a reasonable assurance is had that the mean free path for electrons will be longer than the potential breakdown path in the envelope. A pair of relatively movable disk-shaped contacts or electrodes 34 and 46 are provided within the envelope 34, one of which (such as the lower electrode 66) is movable between open and closed circuit positions as shown by the dotted line 48. The upper electrode 64 may be stationary and is suitably mounted on a conductive rod 56. The lower electrode 416 is movably mounted on a driven rod 52 and is sealed to the end cap 40 by conventional flexible metallic bellows 54.

When the lower electrode 46 is moved from the closed circuit (dotted line 48) position to the lowermost position, as shown in full lines, an are 56 is established between the electrodes 44 and 46, which electrodes vaporize thereby causing the dispersement of metallic particles as well as the release of occluded gases such as hydrogen, oxygen, water vapor, and other gases. The vitreous casing 36 is protected from the metal particles by the provision of a tubular metallic shield 58 which extends substantially throughout the length of the distance between the end caps 38 and 40.

In order to prevent the accumulation of traces of residual gases such as oxygen, water vapor, and hydrogen within the container or envelope 34, a body 66 of getter material is provided between the shield 58 and the easing 36. From time to time the body 66 may be heated to a suitable temperature such as by connecting the body to a pair of electric lead conductors 62 and 64, extending through the dielectric casing 36.

For that purpose the body 60 is composed of a zirconium base binary alloy containing tin and the preferred composition is 24.5 weight per cent tin. The body 60 having the zirconium base binary alloy composition is heated by the lead wires 62 and 64 to a desired temperature of approximately 700C with the lower end thereof, extending below the lead 64 being substantially cooler and at a temperature of approximately 300C, whereby the body 66 functions over a temperature gradient in a manner similar to the body 22, 26, and 40, to adsorb the traces of residual gases of hydrogen, water vapor and oxygen, within the container 34.

Another form of a sealed container having a getter material is a fuel element 65 and 67 shown in FIGS. and 6, respectively. It includes a plurality of cylindrical nuclear fuel pellets 66 of uranium dioxide disposed in end-to-end abutment within a casing or tubular cladding 68. The opposite ends of the cladding 68 are closed by sealing means such as end plugs 70 and 72 that are secured in place by annular welds 74 by which means the interior of the fuel element is hermetically sealed. A plenum chamber 76 is provided at the upper end of the element to accumulate gases due to fission and otherwise.

If the cladding 68 is composed of a zirconium base alloy such as zircaloy, it may be susceptible to embrittlement due to absorption of hydrogen from the water or steam coolant of the reactor. For that reason a body 78 (FIG. 5) is disposed in the chamber 76. The body 78 is composed of a getter material such as a zirconium-base alloy containing tin in an amount varying from about to about 30 weight per cent, a desirable amount of tin being 24.5 weight per cent, for use as a getter at elevated temperatures of operation.

During operation the center of the fuel elements 66 reach an operating temperature of up to 4,200F and the pellet surface temperature being about l,l00F.

The temperature of the cladding is about 660F at the center of the fuel element and is 650F at the end plugs and 72. Inasmuch as the cladding functions as a getter for hydrogen, which would cause hydrogen embrittlement through hydride formation, in the cladding and since the hydrogen diffuses preferentially through the cladding to the cold end plugs 70 and 72 where the hydride would be formed, the body 78 is mounted in the chamber 76, spaced from the uppermost pellet 66, where the body removes hydrogen from the cladding and thus prevents hydride formation in the cladding. The temperature of the body 78 is equal to that of the end plug 70 or somewhat lower than that of the adjacent cladding to assure efficient getter functioning.

The body 78 has a surface configuration similar to that of the cladding 68 and they are in snug fitting sur face-to-surface contact with each other so that hydrogen absorbed by the cladding diffuses to the colder extremity of the cladding where it is absorbed by the body 78. To help maintain its lower temperature the body is preferably in abutment contact with the undersurface of the end plug 70. Accordingly, the body 78 serves the dual purpose of absorbing gases within the chamber 76, as well as of absorbing hydrogen from the cladding.

The fuel element 67 of FIG. 6 has a construction substantially similar to that of the fuel element 65 of FIG. 5. The difference is that the fuel element 67 is provided with a body 80 of getter material having a configuration adapted to the sole function of absorbing deleterious gases from the interior of the cladding 68. Where the cladding 68 (FIG. 6) is composed of a material such as stainless steel, the problem of hydrogen absorption from the water or steam coolant of the reactor is minimal, there is no necessity for a body having the construction of the body 78 (FIG. 5). However, the body 80 is necessary for absorbing the gases, such as hydrogen, nitrogen and water vapor from the interior of the cladding 68. The body 80 has any suitable configuration and has a lower portion 82 extending to the uppermost pellet 66 from which it is separated by a grid 84 for heat insulation. An upper portion 86 of the body 86 is seated within a hole 88 in the end plug 70 in good heat transfer relationship. Thus, the body 86 is operated with a temperature gradient varying from a higher temperature such as about 800C at the lower end adja cent the grid 84 to a lower temperature such as 300C at the upper end, whereby the various gases evolved in the fuel element are absorbed at the temperature appropriate for each gas.

Another form of the invention involving a getter is shown in FIG. 7 in which a pressure vessel for a nuclear reactor is generally indicated at 86. It comprises a core wall 88 having a coolant inlet nozzle 90 and an outlet nozzle 92. A reactor head 94 is mounted on the core wall. For simplicity a water-cooled core in the reactor is not shown. In an enlarged portion of the wall 88 a hole 96 extends into the wall from the outer surface. A body 98 of gettering material is disposed in the hole where it is retained in a fluid-tight manner by a cap 100. A plurality of similar holes with caps 100 are provided at spaced intervals over the entire surface of the wall 88. The several bodies 98 function to absorb hydrogen from the surrounding areas of the wall and thereby prevent failure of the wall by cracking due to hydrogen embrittlement.

In the foregoing description, the specific embodiments of the invention shown in the FIGS. I-7 are provided for illustrative purposes and are not intended to limit the application of the use of a zirconium-base binary alloy with tin to such embodiments. It is understood that such a binary base alloy may be used in any hermetically sealed device in which gases or vapors are evolved during operation of the device which are chemically or physically absorbable by the alloy. The zirconium base binary alloy with tin is particularly adaptable to devices where hydrogen is the primary problem instead of oxygen and water vapor. For example, under some circumstances, it may be desirable to remove hydrogen to prevent hydrogen embrittlement of a metal cladding or to minimize the generation of excessive pressures within a hermetically sealed container.

While the best known embodiments of the invention have been illustrated and described in detail, it is understood that the invention is not limited thereto or thereby.

What is claimed is:

l. A hermetically sealed container comprising a member subject to development of elevated temperatures, the member being adversely affected by reaction with traces of residual gases, the container and its contents including said member having occluded and adsorbed thereon traces of said gases which are evolved during operation of the member, and means within the container for reacting with and adsorbing said residual gases, said means comprising a body of zirconium base alloy consisting essentially of, by weight, from about 10 to 30 percent tin, the balance being zirconium except for incidential impurities, and means for heating the body to a temperature ranging from about 300 to about 700C.

2. The container of claim 1 in which the body is composed of about 24.5 weight per cent tin and the balance is zirconium.

3. The container of claim 1 in which a portion of the body is so disposed and constructed as to be readily heated by the heating means to a temperature higher than the temperature of another portion of the body.

4. The container of claim 3 in which the body is operative over a temperature gradient ranging from about 300 to about 700C to react with and remove residual gases.

5. in a sealed container, a getter material for reacting with and adsorbing traces of residual gases within the container, the getter material comprising a body of zirconium base alloy consisting essentially of from about 10 to 30 weight per cent tin and balance being zirconium except for incidental impurities, and means for heating the body to a temperature ranging from about 300 to about 700C.

6. The container of claim 5 wherein the body is composed of about 24.5 weight per cent tin and the balance is zirconium. 

2. The container of claim 1 in which the body is composed of about 24.5 weight per cent tin and the balance is zirconium.
 3. The container of claim 1 in which a portion of the body is so disposed and constructed as to be readily heated by the heating means to a temperature higher than the temperature of another portion of the body.
 4. The container of claim 3 in which the body is operative over a temperature gradient ranging from about 300* to about 700*C to react with and remove residual gases.
 5. In a sealed container, a getter material for reacting with and adsorbing traces of residual gases within the container, the getter material comprising a body of zirconium base alloy consisting essentially of from about 10 to 30 weight per cent tin and balance being zirconium except for incidental impurities, and means for heating the body to a temperature ranging from about 300* to about 700*C.
 6. The container of claim 5 wherein the body is composed of about 24.5 weight per cent tin and the balance is zirconium. 